1. Field of the Invention
The invention relates to a shift control device and a shift control method for an automatic transmission. Particularly, the invention relates to a shift control device and a shift control method for an automatic transmission that execute a squat control.
2. Description of the Related Art
There is a known related-art shift control device of an automatic transmission of the aforementioned type that performs a squat control of forming the first speed change step after temporarily forming a speed change step other than the first speed change step so as to reduce the speed change step shifting shock when the select range is switched from the N range to a travel range (see, for example, Japanese Patent Application Publication No. 4-366066 (JP-A-4-366066)).
Another known shift control device of an automatic transmission is a device that performs a shift control of an automatic transmission as shown in FIG. 10 (see, for example, Japanese Patent Application Publication No. 2005-36934 (JP-A-2005-36934)). In the case where the automatic transmission is switched from the neutral state to a state in which the second speed change step that is less in speed change ratio than the first speed change step is established, this shift control device of the automatic transmission sequentially engages a fourth clutch C4 and a third brake B3 for forming the second speed change step subsequently to the engagement of the first clutch C1 for forming the first speed change step so as to reduce the speed change step shifting shock even when the vehicle is started from the standing state in the second speed change step.
However, in the case where the squat control described in Japanese Patent Application Publication No. 4-366066 (JP-A-4-366066) is performed by the shift control device of the automatic transmission described in Japanese Patent Application Publication No. 2005-36934 (JP-A-2005-36934), the switching of the automatic transmission from the neutral state to the state in which the second speed change step is established is performed by sequentially engaging the first clutch C1 and the fourth clutch C4, and engaging a second brake B2 capable of fine control of capacity, and releasing the second brake B2, and then engaging the third brake B3 capable of withstanding the torque occurring at the time of the standing-start. Therefore, the speed change step shifts from the second speed change step to the first speed change step, and then the second speed change step is formed again. Hence, there is a problem of occurrence of a speed change step shift shock.